Wealth in waste

About 150 million tonnes of forestry waste and 350 million tonnes of agricultural residue are produced in India every year. However, a major portion of the wastes is not utilised. Scientists in India have devised pyrolysis method to convert biomass into charcoal briquettes that could benefit users and generate employment in rural areas. Pyrolysis is a process in which biomass is charred at 250-500C for partial removal of volatiles. The stable pyrolyser made up of bricks and fine clay is filled with biomass. Each pyrolysis operation with a 100 kg char yield takes between 6-8 hours. The charcoal obtained after the process is crushed into fine powder. After fine grinding, binder of about 10 per cent by weight is mixed into the char powder. About six per cent clay is also mixed to increase the agglomeration of the mixture. The mixture is then converted into briquettes by applying pressure to small pieces of char particles with or without a binder or compacting them .